Operating under limited resources poses significant demands on the cognitive system. Here we demonstrate that people under time scarcity failed to detect time-saving cues as they occur in the environment (Experiment 1a). These time-saving cues, if noticed, would have saved time for the time-poor participants. Moreover, the visuospatial proximity of the time-saving cues to the focal task determined successful detection, suggesting that scarcity altered the spatial scope of attention (Experiment 1b & 1c). People under time scarcity were also more likely to forget previous instructions to execute future actions (Experiment 2). These instructions, if remembered and followed, would have saved time for the time-poor participants. Failures of online detection and prospective memory are problematic because they cause neglect and forgetting of beneficial information, perpetuating the condition of scarcity. The current study provides a new cognitive account for the counterproductive behaviors in the poor, and relevant implications for interventions.